Forest Influences on Climate and Water Resources at the Landscape to Regional Scale - Landscape Ecology for Sustainable Environment and Culture - page 302

begin to know that forests influence redistribution of global solar energy and
energy budget on earth, thus play a key role in the global hydrologic cycle (Jung
et al. 2010 ). It has become possible to trace the movements of water vapor and
atmospheric gases to develop a clearer idea of the role played by forests in
moderating or regulating rainfall in different part of the world. For example, in
temperate regions and tropical regions such as Southeast Asia, the main source of
water vapor in the atmosphere is from evaporation at the surface of the oceans. In
the Amazon Basin, however, nearly 50 % of water vapor in the atmosphere in the
region of Manaus and Belém appears to be 'recycled' from the forest. Oyebande
( 1988 ), Eltahir and Bras ( 1993 ), and Dickinson et al. ( 1993 ) provide good sum-
maries of the effects of forests on rainfall and water yield in the tropics. Garcia-
Carreras and Parker ( 2011 ) recently reports deforestation may intensify rainfall in
cut area and decrease rainfall of the surrounding areas and threats remaining rain
forests in western Africa.
In general, majority of our knowledge on forest-climate-water relations is
derived from small watershed studies, thus the influences of forests on local and
global climate and water supply are still open for debate (Bonan 2008 ; Ellison
et al. 2012 ; van der Ent et al. 2012 ). Our current knowledge about forests' role in
moderating climate and water resources at a large watershed (Wei et al. 2008 ; Lin
and Wei 2008 ; Wei and Zhang 2010 ) or regional scale is limited, and a broad
understanding of forest-water-climate interactions is needed for determining forest
management strategies in climate change mitigation and adaptation.
The overall goal of this study is to provide an in depth understanding of forest-
climate-water interactions at regional to global scale by synthesizing recent
scientific literature on the influences of forests on climate and water resources.
Specific objectives are to: (1) present state of art of our understanding of the
mechanisms of interactions of forests and climate and water resources at the
landscape and regional scale, (2) present two case studies that examine the influ-
ence of forests on climate and water resources, and (3) identify research gaps that
help guide future studies that can help forest management for global change mit-
igation and adaptation.
15.2 Principles of Forest Influences on Climate
and Water Resources
Forests influence climate and water resources through their physical and biological
functions that affect the energy, water, and biogeochemical balances (Zhao and
Pitman, 2010). Key mechanisms and processes within a forest landscape are
illustrated to demonstrate the close interactions between atmosphere and land
surfaces and the tight forest-climate-water relationship (Fig. 15.1 ).